Migration corridors for birds breeding in NOMA

Birds migrating to the Barents Sea during autumn from colonies in the Norwegian and North Seas generally move along the Norwegian coast (Figure fig-oa-mig). Within the Barents Sea, movement can be seen across the entire shelf sea. Most migrations of Norwegian seabirds occur in the western and southern part of the shelf sea with a lesser utilization of the eastern part. The main migration route from the Barents Sea to main overwintering areas around Iceland, southern Greenland and the Northwest Atlantic (Figure 18 and Figure 19) follows the east Greenland pack ice and coastline along general wind corridors (Amelineau et al. in review). Some birds from the North Sea also cross the Northeast Atlantic directly to reach their overwintering areas in the Northwest Atlantic. The return migration to breeding sites in NOMA in turn is more diffuse across the Northeast Atlantic (Figure fig-oa-mig), similar to the more diffuse timing of this return migration (Figure fig-oa-mig-time). Across all six pelagic species three clear migration periods are visible in the Barents and Norwegian Sea areas (Figure fig-oa-mig-time). These seemingly correspond to (1) the migration from the colony to autumn staging areas in August and September, (2) the migration autumn staging areas to overwintering areas in October to December, and (3) the return migration from overwintering areas to the colony in January to May. Species- and NOMA-specific variability in these migration timings is also apparent, with birds breeding in the Norwegian Sea migration generally early than birds breeding in the Barents Sea and black-legged kittiwakes migrating early than little auks (Figure fig-oa-mig-time).